The research on this topic has been discussed on HN multiple times. It is indeed hard to look up previous discussions, but the conclusion is always inconclusive... one thing everyone seems to agree nowadays is that measuring LOC is a bad proxy for programmer productivity, specially when you take code maintenance into consideration (which very few research papers do), and that types do have a small, but measurable effect on improving quality (though whether that's at the cost of productivity is still unclear as far as I know - yes, programmers need to spend a bit more time to declare their types, but without them they have to spend more time every time they need to call anything).